{"id":5455,"date":"2025-12-17T11:15:04","date_gmt":"2025-12-17T03:15:04","guid":{"rendered":"https:\/\/www.xttblog.com\/?p=5455"},"modified":"2025-12-17T11:15:04","modified_gmt":"2025-12-17T03:15:04","slug":"java-%e5%8d%95%e4%be%8b%e6%a8%a1%e5%bc%8f%e7%bb%88%e4%ba%8e%e6%9c%89%e6%95%91%ef%bc%81jdk-26-lazyconstants-%e7%bb%88%e7%bb%93%e6%89%8b%e5%86%99%e7%ba%bf%e7%a8%8b%e5%ae%89%e5%85%a8%e6%97%b6%e4%bb%a3","status":"publish","type":"post","link":"https:\/\/www.xttblog.com\/?p=5455","title":{"rendered":"Java \u5355\u4f8b\u6a21\u5f0f\u7ec8\u4e8e\u6709\u6551\uff01JDK 26 LazyConstants \u7ec8\u7ed3\u624b\u5199\u7ebf\u7a0b\u5b89\u5168\u65f6\u4ee3"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\">Java \u53c8\u6539\u4e86\uff0c\u8fd9\u6b21\u662f JEP 502 \u7a33\u5b9a\u503c Stable Values \u6539\u4e3a JEP 526 \u60f0\u6027\u5e38\u91cf Lazy Constants \u4e86\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u8fd9\u610f\u5473\u7740\u4ec0\u4e48\u5462\uff1f\u610f\u5473\u7740\u6211\u534a\u5e74\u524d\u5199\u7684\u4e00\u7bc7\u6587\u7ae0\u300a<a href=\"https:\/\/mp.weixin.qq.com\/s\/Y6P08Yzer06Wehj7dc9qcw\">https:\/\/mp.weixin.qq.com\/s\/Y6P08Yzer06Wehj7dc9qcw<\/a>\u300b\uff0c\u90e8\u5206\u5185\u5bb9\u5931\u6548\u4e86\uff0c\u5176\u4e2d\u7684\u7c7b\u540d\u7b49\u505a\u4e86\u4e00\u4e9b\u53d8\u66f4\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u6211\u770b\u4e86\u4e00\u4e0b\u8fd9\u4e2a<code>https:\/\/openjdk.org\/jeps\/526<\/code>\u5185\u5bb9\uff0c\u8fd9\u4e9b\u6539\u52a8\u88ab JDK \u793e\u533a\u8bf4\u7684\u51a0\u5195\u5802\u7687\u7684\uff0c\u603b\u4e4b\u5c31\u662f\u8a00\u4e4b\u6709\u7406\u3002\u6240\u4ee5\uff0c\u63a5\u4e0b\u6765\u6211\u4eec\u5c31\u4e00\u8d77\u6765\u4e00\u6b21 Java 26 \u65b0\u7279\u6027\u6df1\u5ea6\u89e3\u6790\uff0c\u4ece Stable Values \u5230 Lazy Constants\uff0c\u5355\u4f8b\u6a21\u5f0f\u8fce\u6765\u7684\u9769\u65b0\uff01<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">\u5ef6\u8fdf\u521d\u59cb\u5316\u7684\u56f0\u5883<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">\u4f17\u6240\u5468\u77e5\uff0c\u5728 Java \u5f00\u53d1\u4e2d\uff0c\u6211\u4eec\u7ecf\u5e38\u4f1a\u9047\u5230\u4e00\u4e2a\u7ecf\u5178\u77db\u76fe\uff0c<code>\u542f\u52a8\u6027\u80fd<\/code> vs <code>\u8fd0\u884c\u65f6\u6027\u80fd<\/code>\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u6bd4\u5982\uff0c\u4e00\u4e2a\u5927\u578b\u4f01\u4e1a\u7ea7\u5e94\u7528\uff0c\u542f\u52a8\u65f6\u9700\u8981\u521d\u59cb\u5316\u6570\u5341\u4e2a\u670d\u52a1\u7ec4\u4ef6\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>class Application {\n    static final OrderController ORDERS = new OrderController();\n    static final ProductRepository PRODUCTS = new ProductRepository();\n    static final UserService USERS = new UserService();\n    \/\/ ... \u8fd8\u6709\u51e0\u5341\u4e2a\n}<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u6bcf\u4e2a\u7ec4\u4ef6\u7684\u6784\u9020\u53ef\u80fd\u6d89\u53ca\u6570\u636e\u5e93\u8fde\u63a5\u3001\u914d\u7f6e\u52a0\u8f7d\u3001\u8d44\u6e90\u5206\u914d\u7b49\u8017\u65f6\u64cd\u4f5c\uff0c\u5bfc\u81f4\u5e94\u7528\u542f\u52a8\u7f13\u6162\u3002\u4f46\u5f88\u591a\u65f6\u5019\uff0c\u67d0\u4e9b\u7ec4\u4ef6\u53ef\u80fd\u5728\u6574\u4e2a\u5e94\u7528\u751f\u547d\u5468\u671f\u4e2d\u90fd\u4e0d\u4f1a\u88ab\u4f7f\u7528\uff0c\u6211\u4eec\u5374\u5df2\u7ecf\u4e3a\u5b83\u4eec\u4ed8\u51fa\u4e86\u542f\u52a8\u65f6\u95f4\u6210\u672c\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u6b64\u65f6\uff0c\u63a8\u8350\u7684\u505a\u6cd5\u6216\u4f20\u7edf\u7684\u89e3\u51b3\u65b9\u6848\u662f\u4f7f\u7528\u5ef6\u8fdf\u521d\u59cb\u5316\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>class OrderController {\n    private Logger logger = null;\n\n    Logger getLogger() {\n        if (logger == null) {\n            logger = Logger.create(OrderController.class);\n        }\n        return logger;\n    }\n}<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u4f46\u8fd9\u4e5f\u5e26\u6765\u4e86\u65b0\u95ee\u9898\u3002<\/p>\n\n\n\n<ol class=\"wp-block-list\"><li>\u7ebf\u7a0b\u5b89\u5168\u95ee\u9898\uff1a\u591a\u7ebf\u7a0b\u73af\u5883\u4e0b\u53ef\u80fd\u521b\u5efa\u591a\u4e2a\u5b9e\u4f8b<\/li><li>\u6027\u80fd\u635f\u5931\uff1a\u5931\u53bb<code>final<\/code>\u5b57\u6bb5\u7684\u5e38\u91cf\u6298\u53e0\u4f18\u5316<\/li><li>\u4ee3\u7801\u4e11\u964b\uff1a\u9700\u8981\u663e\u5f0f\u5224\u7a7a\uff0c\u589e\u52a0\u7ef4\u62a4\u6210\u672c<\/li><\/ol>\n\n\n\n<p class=\"wp-block-paragraph\">\u4e3a\u6b64\uff0c\u6211\u4eec\u53ef\u80fd\u4f1a\u4f7f\u7528\u5355\u4f8b\u6a21\u5f0f\uff0c\u4f46\u662f\u8981\u77e5\u9053\u5355\u4f8b\u6a21\u5f0f\u7684\u5199\u6cd5\u9ad8\u8fbe 7 \u79cd\uff0c\u9762\u8bd5\u65f6\u5e38\u88ab\u540a\u6253\u3002\u5355\u4f8b\u867d\u7136\u80fd\u89e3\u51b3\u7ebf\u7a0b\u5b89\u5168\u95ee\u9898\uff0c\u4f46\u662f\u6bcf\u6b21\u53ef\u80fd\u90fd\u6709 if \u5224\u65ad\uff0c\u8fd8\u6709\u65e0\u6cd5\u5229\u7528 final \u7279\u6027\uff0c\u5f15\u5165\u4ee3\u7801\u590d\u6742\u6027\u7b49\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u4e8e\u662f\uff0cJDK 25 \u5f15\u5165\u4e86<code>Stable Values<\/code>\u548c JDK 26 \u8fdb\u5316\u7684<code>Lazy Constants<\/code>\uff0c\u5c31\u662f\u4e3a\u4e86\u89e3\u51b3\u8fd9\u4e9b\u56f0\u5883\u800c\u751f\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">JEP 502 vs JEP 526<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">\u4ece JEP 502 Stable Values \u5230 JEP 526 Lazy Constants\uff0c\u672c\u8d28\u662f\u4e00\u6b21\u91cd\u8981\u7684 API \u91cd\u5851\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">JDK 25 \u7684 Stable Values<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Stable Values \u662f JDK 25 \u7684\u4e00\u6b21\u5c1d\u8bd5\uff0c\u662f\u4e00\u4e2a\u9884\u89c8\u7279\u6027\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">JEP 502 \u5728 JDK 25 \u4e2d\u9996\u6b21\u5f15\u5165<code>StableValue<\/code> API\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>class OrderController {\n    private final StableValue&lt;Logger&gt; logger = StableValue.of();\n\n    Logger getLogger() {\n        return logger.orElseSet(() -&gt; \n            Logger.create(OrderController.class));\n    }\n}<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u8fd9\u4e2a\u8bbe\u8ba1\u89e3\u51b3\u4e86\u4e0a\u9762\u63d0\u5230\u7684\u4e00\u4e9b\u6838\u5fc3\u95ee\u9898\uff0c\u4f46 Java \u793e\u533a\u53cd\u9988\u66b4\u9732\u4e86\u4e00\u4e9b\u4e0d\u8db3\u3002<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>API \u5c42\u7ea7\u504f\u4f4e\uff1a<code>orElseSet()<\/code>\u7b49\u64cd\u4f5c\u8fc7\u4e8e\u8d34\u8fd1\u5e95\u5c42\u5b9e\u73b0<\/li><li>\u547d\u540d\u4e0d\u591f\u76f4\u89c2\uff1a\u201cStableValue\u201d\u6ca1\u6709\u6e05\u6670\u4f20\u8fbe\u201c\u5ef6\u8fdf\u521d\u59cb\u5316\u5e38\u91cf\u201d\u7684\u610f\u56fe<\/li><li>\u4f7f\u7528\u65b9\u5f0f\u7e41\u7410\uff1a\u9700\u8981\u6bcf\u6b21\u90fd\u8c03\u7528<code>orElseSet()<\/code>\u65b9\u6cd5<\/li><\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">\u6240\u4ee5\uff0cJDK 26 \u8fdb\u884c\u4e86\u6539\u7248\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">JDK 26 \u7684 Lazy Constants<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">JDK 26 \u542c\u53d6\u4e86\u5efa\u8bae\uff0c\u5bf9\u8fd9\u4e2a\u7279\u6027\u8fdb\u884c\u4e86\u9769\u65b0\uff0c\u4e5f\u5c31\u662f\u6211\u4eec\u73b0\u5728\u770b\u5230\u7684 Lazy Constants\uff0c\u76f8\u5f53\u4e8e\u662f\u7b2c\u4e8c\u6b21\u9884\u89c8\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u8fd9\u6b21\u9884\u89c8\u662f\u57fa\u4e8e\u5f00\u53d1\u8005\u7684\u53cd\u9988\uff0cJEP 526 \u8fdb\u884c\u4e86\u91cd\u5927\u8c03\u6574\uff0c\u53ef\u4ee5\u6982\u62ec\u4e3a<code>\u505a\u51cf\u6cd5<\/code>\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u9996\u5148\u662f\uff0c<code>API \u6838\u5fc3\u91cd\u547d\u540d<\/code>\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>\/\/ JDK 25\nStableValue&lt;Logger&gt; logger = StableValue.of();\n\n\/\/ JDK 26\nLazyConstant&lt;Logger&gt; logger = LazyConstant.of(() -&gt; \n    Logger.create(OrderController.class));<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u7740\u80cc\u540e\u7684\u8003\u91cf\u662f\uff0cLazyConstant \u5ef6\u8fdf\u5e38\u91cf\u6bd4 StableValue \u7a33\u5b9a\u503c\u66f4\u51c6\u786e\u5730\u63cf\u8ff0\u4e86\u7279\u6027\u672c\u8d28\uff0c\u8fd9\u662f\u4e00\u4e2a<code>\u4f1a\u88ab\u5ef6\u8fdf\u521d\u59cb\u5316\u4f46\u4e4b\u540e\u4e0d\u53ef\u53d8\u7684\u5e38\u91cf<\/code>\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u5176\u6b21\u662f\u79fb\u9664\u5e95\u5c42\u64cd\u4f5c\uff0c\u805a\u7126\u9ad8\u5c42\u7528\u4f8b\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">JDK 26 \u79fb\u9664\u4e86\u4ee5\u4e0b\u5bb9\u6613\u8bef\u7528\u7684\u65b9\u6cd5\u3002<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li><code>orElseSet(Supplier)<\/code>\uff0c\u9700\u8981\u624b\u52a8\u8c03\u7528\u521d\u59cb\u5316<\/li><li><code>setOrThrow(T)<\/code>\uff0c\u5e95\u5c42\u8bbe\u7f6e\u64cd\u4f5c<\/li><li><code>trySet(T)<\/code>\uff0c\u5c1d\u8bd5\u8bbe\u7f6e\u64cd\u4f5c<\/li><\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">\u4e3a\u4ec0\u4e48\u8981\u8fd9\u6837\u505a\u5462\uff1f\u56e0\u4e3a\u793e\u533a\u8ba4\u4e3a\u8fd9\u4e9b\u64cd\u4f5c\u8981\u6c42\u5f00\u53d1\u8005\u7406\u89e3\u5e95\u5c42\u540c\u6b65\u673a\u5236\uff0c\u5bb9\u6613\u5f15\u53d1\u7ade\u6001\u6761\u4ef6\u3002\u6240\u4ee5\uff0cJDK 26 \u6539\u4e3a<code>\u5f3a\u5236\u5728\u6784\u9020\u65f6\u63d0\u4f9b\u8ba1\u7b97\u51fd\u6570<\/code>\uff0c\u5c06\u7ebf\u7a0b\u5b89\u5168\u5b8c\u5168\u5c01\u88c5\u5728 API \u5185\u90e8\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u63a5\u4e0b\u6765\u662f\u96c6\u5408 API \u7684\u6df1\u5ea6\u96c6\u6210\u3002\u5c06\u96c6\u5408\u76f8\u5173\u5de5\u5382\u65b9\u6cd5\u8fc1\u79fb\u5230\u6807\u51c6\u63a5\u53e3\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>\/\/ JDK 25\nStableValue.list(size, creator)\n\n\/\/ JDK 26\nList.ofLazy(size, creator)  \/\/ \u66f4\u81ea\u7136\u7684 API\nMap.ofLazy(keySet, creator)  \/\/ \u65b0\u589e\u5bf9 Map \u7684\u652f\u6301<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u8fd9\u6837\u505a\u7684\u597d\u5904\u662f\uff0c\u63d0\u5347 API \u53ef\u53d1\u73b0\u6027\uff0c\u7b26\u5408 Java \u5f00\u53d1\u8005\u4f7f\u7528\u4e60\u60ef\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u6700\u540e\u662f\u7981\u6b62 null \u503c\u3002JDK 26 \u660e\u786e\u7981\u6b62\u8ba1\u7b97\u51fd\u6570\u8fd4\u56de null\uff0c\u8fd9\u4e0e<code>ScopedValue<\/code>\u7b49\u73b0\u4ee3 API \u4fdd\u6301\u4e00\u81f4\uff0c\u7b80\u5316\u5b9e\u73b0\u5e76\u63d0\u5347\u6027\u80fd\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Lazy Constants \u7684\u6838\u5fc3\u4f18\u52bf<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">\u9996\u5148\u662f\u7ebf\u7a0b\u5b89\u5168\u7684\u5355\u4f8b\u521d\u59cb\u5316\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>class Application {\n    static final LazyConstant&lt;OrderController&gt; ORDERS = \n        LazyConstant.of(OrderController::new);\n\n    public static OrderController orders() {\n        return ORDERS.get(); \/\/ \u7ebf\u7a0b\u5b89\u5168\uff0c\u4ec5\u521d\u59cb\u5316\u4e00\u6b21\n    }\n}<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u4ee5\u540e\u7684\u5355\u4f8b\uff0c\u4e0e synchronized\u3001volatile \u7b49\u53ef\u80fd\u5c31\u65e0\u5173\u4e86\u3002\u8981\u77e5\u9053\uff0c\u8fd9\u5176\u4e2d\u6bd4\u8f83\u5173\u952e\u7684\u662f\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li><code>get()<\/code>\u65b9\u6cd5\u4fdd\u8bc1\u6070\u597d\u4e00\u6b21\u521d\u59cb\u5316<\/li><li>\u65e0\u9700<code>synchronized<\/code>\uff0c\u4e5f\u65e0\u9700<code>volatile<\/code><\/li><li>\u5373\u4f7f\u5728\u9ad8\u5e76\u53d1\u573a\u666f\u4e0b\u4e5f\u5b89\u5168<\/li><\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">\u5176\u6b21\u662f\uff0cJVM \u5e38\u91cf\u6298\u53e0\u4f18\u5316\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u5f53<code>LazyConstant<\/code>\u5b58\u50a8\u5728<code>final<\/code>\u5b57\u6bb5\u4e2d\u4e14\u88ab\u521d\u59cb\u5316\u540e\uff0cJIT \u53ef\u4ee5\u5c06\u5176\u5185\u5bb9\u89c6\u4e3a<code>\u771f\u6b63\u7684\u5e38\u91cf<\/code>\uff0c\u8fdb\u884c\u4ee5\u4e0b\u4f18\u5316\u3002<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>\u5185\u8054\u5c55\u5f00\uff1a\u76f4\u63a5\u5d4c\u5165\u5e38\u91cf\u503c<\/li><li>\u6b7b\u7801\u6d88\u9664\uff1a\u57fa\u4e8e\u5e38\u91cf\u503c\u5220\u9664\u4e0d\u53ef\u8fbe\u4ee3\u7801<\/li><li>\u7b80\u5316\u8ba1\u7b97\uff1a\u7f16\u8bd1\u65f6\u5b8c\u6210\u5e38\u91cf\u8868\u8fbe\u5f0f\u6c42\u503c<\/li><\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">\u8fd9\u4e0e JDK \u5185\u90e8\u4f7f\u7528\u7684<code>@Stable<\/code>\u6ce8\u89e3\u6548\u679c\u76f8\u540c\uff0c\u4f46\u73b0\u5728\u662f<code>\u5b89\u5168\u3001\u516c\u5f00\u7684 API<\/code>\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u63a5\u7740\u662f\u5ef6\u8fdf\u521d\u59cb\u5316\u94fe\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>class OrderController {\n    \/\/ Logger\u5728\u9996\u6b21\u4f7f\u7528\u65f6\u624d\u521d\u59cb\u5316\n    private final LazyConstant&lt;Logger&gt; logger = \n        LazyConstant.of(() -&gt; Logger.create(OrderController.class));\n\n    void submitOrder(User user, List&lt;Product&gt; products) {\n        logger.get().info(\"Order submitted\");\n    }\n}\n\nclass Application {\n    \/\/ OrderController\u5728\u9996\u6b21\u4f7f\u7528\u65f6\u624d\u521d\u59cb\u5316\n    static final LazyConstant&lt;OrderController&gt; ORDERS = \n        LazyConstant.of(OrderController::new);\n}<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u6574\u4e2a\u4f9d\u8d56\u94fe\u90fd\u662f<code>\u6309\u9700\u521d\u59cb\u5316<\/code>\uff0c\u6781\u5927\u6539\u5584\u542f\u52a8\u6027\u80fd\u3002\u4f46\u662f\uff0c\u542f\u52a8\u901f\u5ea6\u52a0\u5feb\u4e86\u4e4b\u540e\uff0c\u9996\u6b21\u8bbf\u95ee\u5c31\u4f1a\u76f8\u5bf9\u7684\u66f4\u6162\u4e00\u4e9b\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">\u4e94\u79cd\u5355\u4f8b\u6a21\u5f0f\u7684\u65b0\u5b9e\u73b0<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">\u6709\u4e86 JDK 26\uff0c\u4ee5\u524d\u7684 7 \u79cd\u5355\u4f8b\u5b9e\u73b0\uff0c\u53ef\u4ee5\u6539\u4e3a\u73b0\u5728\u7684 5 \u79cd\u5355\u4f8b\u5b9e\u73b0\u4e86\u3002\u5f53\u7136\uff0c\u4ee5\u524d\u7684 7 \u4e2d\u5355\u4f8b\u5b9e\u73b0\uff0c\u4e5f\u4e0d\u662f\u4e0d\u80fd\u7528\u3002\u5408\u8d77\u6765\u5c31\u662f 12 \u79cd\u5b9e\u73b0\u4e86\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u63a5\u4e0b\u6765\uff0c\u6211\u4eec\u5c31\u4e00\u8d77\u770b\u770b\u65b0\u7684\u4e94\u79cd\u5355\u4f8b\u5b9e\u73b0\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\u9759\u6001\u5b57\u6bb5<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u793e\u533a\u662f\u975e\u5e38\u63a8\u8350\u8fd9\u79cd\u9759\u6001\u5b57\u6bb5\u7684\u5355\u4f8b\u6a21\u5f0f\u7684\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>public class DatabaseService {\n    private static final LazyConstant&lt;DatabaseService&gt; INSTANCE = \n        LazyConstant.of(DatabaseService::new);\n\n    public static DatabaseService getInstance() {\n        return INSTANCE.get();\n    }\n\n    private DatabaseService() {\n        \/\/ \u6602\u8d35\u7684\u521d\u59cb\u5316\u64cd\u4f5c\n        connectToDatabase();\n    }\n}<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u8fd9\u79cd\u5199\u6cd5\u7684\u4f18\u70b9\u662f\uff0c\u7b80\u6d01\u3001\u7ebf\u7a0b\u5b89\u5168\u3001\u6027\u80fd\u6700\u4f18\uff0c\u4e14\u9002\u5408\u7edd\u5927\u591a\u6570\u5355\u4f8b\u573a\u666f\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\u679a\u4e3e\u5355\u4f8b\u7684\u589e\u5f3a\u7248<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u7b2c\u4e8c\u79cd\u65b9\u5f0f\uff0c\u8fd8\u662f\u4f7f\u7528\u679a\u4e3e\uff0c\u540c\u65f6\u7ed3\u5408<code>LazyConstant<\/code>\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>public enum ConfigManager {\n    INSTANCE;\n\n    private final LazyConstant&lt;Config&gt; config = \n        LazyConstant.of(() -&gt; loadConfigFromFile());\n\n    public Config getConfig() {\n        return config.get();\n    }\n}<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u8fd9\u79cd\u5199\u6cd5\u7684\u4f18\u70b9\u662f\uff0c\u5929\u7136\u9632\u6b62\u53cd\u5c04\u653b\u51fb\uff0c\u914d\u7f6e\u5ef6\u8fdf\u52a0\u8f7d\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\u5e26\u53c2\u6570\u7684\u5355\u4f8b\u6c60<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u4e00\u6b21\u5b9e\u73b0\u6216\u6279\u91cf\u5b9e\u73b0\u5355\u4f8b\u6c60\uff0c\u7528\u6cd5\u5982\u4e0b\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>public class CacheService {\n    private final String cacheName;\n\n    private static final Map&lt;String, LazyConstant&lt;CacheService&gt;&gt; INSTANCES =\n        Map.ofLazy(Set.of(\"user\", \"product\", \"order\"),\n                   name -&gt; new CacheService(name));\n\n    public static CacheService getInstance(String name) {\n        return INSTANCES.get(name);\n    }\n\n    private CacheService(String cacheName) {\n        this.cacheName = cacheName;\n        initializeCache();\n    }\n}<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u8fd9\u662f JDK 26 \u65b0\u589e\u7684\u5199\u6cd5\uff0c\u901a\u8fc7<code>Map.ofLazy()<\/code>\u5b9e\u73b0\u5e26\u53c2\u6570\u7684\u5355\u4f8b\u6c60\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\u8d44\u6e90\u6c60\u5316<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u63a5\u4e0b\u6765\uff0c\u9488\u5bf9\u5404\u79cd\u8fde\u63a5\u6c60\uff0c\u53ef\u4ee5\u8fdb\u884c\u8d44\u6e90\u6c60\u5316\u4e86\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>class ConnectionPool {\n    static final List&lt;LazyConstant&lt;Connection&gt;&gt; POOL = \n        List.ofLazy(10, _ -&gt; createConnection());\n\n    public static Connection getConnection() {\n        long index = Thread.currentThread().threadId() % 10;\n        return POOL.get((int)index).get();\n    }\n}<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u8fd9\u4e2a\u9002\u7528\u573a\u666f\u5c31\u6bd4\u8f83\u591a\u4e86\uff0c\u6570\u636e\u5e93\u8fde\u63a5\u6c60\u3001\u7ebf\u7a0b\u6c60\u7b49\u8d44\u6e90\u7ba1\u7406\u90fd\u53ef\u4ee5\u91c7\u53d6\u8fd9\u79cd\u5199\u6cd5\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">ServiceLoader \u96c6\u6210<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u4e0e ServiceLoader \u7684\u96c6\u6210\u540e\u7eed\u4e5f\u5c06\u975e\u5e38\u5e38\u7528\u3002\u800c\u4e14\uff0c\u67d0\u4e9b\u81ea\u5b9a\u4e49\u7684 Spring bean \u4e5f\u53ef\u80fd\u4f1a\u7528\u4e0a\u5ef6\u8fdf\u52a0\u8f7d\u3002\u4ece\u800c\u8ba9 Java \u5e94\u7528\u7684\u542f\u52a8\u901f\u5ea6\u5927\u5e45\u589e\u52a0\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>public class MyServiceProvider implements MyService {\n    private static final LazyConstant&lt;MyServiceProvider&gt; INSTANCE = \n        LazyConstant.of(MyServiceProvider::new);\n\n    \/\/ ServiceLoader\u4f1a\u8c03\u7528\u6b64\u65b9\u6cd5\n    public static MyServiceProvider provider() {\n        return INSTANCE.get();\n    }\n}<\/code><\/pre>\n\n\n\n<h2 class=\"wp-block-heading\">\u6027\u80fd\u5bf9\u6bd4\uff1a\u6570\u636e\u8bf4\u8bdd<\/h2>\n\n\n\n<table class=\"wp-block-table\"><thead><tr><th>\u5b9e\u73b0\u65b9\u5f0f<\/th><th>\u9996\u6b21\u8c03\u7528\u5f00\u9500<\/th><th>\u540e\u7eed\u8c03\u7528\u5f00\u9500<\/th><th>\u7ebf\u7a0b\u5b89\u5168<\/th><th>\u5e38\u91cf\u6298\u53e0<\/th><th>\u4ee3\u7801\u590d\u6742\u5ea6<\/th><\/tr><\/thead><tbody><tr><td>\u997f\u6c49\u5f0f<\/td><td>\u65e0<\/td><td>\u6700\u4f4e<\/td><td>\u5b89\u5168<\/td><td>\u652f\u6301<\/td><td>\u4f4e<\/td><\/tr><tr><td>\u53cc\u91cd\u68c0\u67e5\u9501\u5b9a<\/td><td>\u4e2d\u7b49<\/td><td>\u4f4e<\/td><td>\u5b89\u5168<\/td><td>\u4e0d\u652f\u6301<\/td><td>\u9ad8<\/td><\/tr><tr><td>\u9759\u6001\u5185\u90e8\u7c7b<\/td><td>\u65e0<\/td><td>\u6700\u4f4e<\/td><td>\u5b89\u5168<\/td><td>\u652f\u6301<\/td><td>\u4e2d<\/td><\/tr><tr><td>LazyConstants<\/td><td>\u6781\u4f4e<\/td><td>\u6700\u4f4e<\/td><td>\u5b89\u5168<\/td><td>\u652f\u6301<\/td><td>\u6781\u4f4e<\/td><\/tr><\/tbody><\/table>\n\n\n\n<p class=\"wp-block-paragraph\">\u6839\u636e OpenJDK \u5b98\u65b9\u6570\u636e\u5fae\u57fa\u51c6\u6d4b\u8bd5\u7ed3\u679c\u8868\u660e\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>\u76f8\u6bd4<code>volatile<\/code>\u53cc\u91cd\u68c0\u67e5\u9501\u5b9a\uff0cLazyConstants\u540e\u7eed\u8c03\u7528\u6027\u80fd\u63d0\u5347 15-30%<\/li><li>\u542f\u52a8\u65f6\u672a\u4f7f\u7528\u7684\u7ec4\u4ef6\uff0c\u8282\u7701\u521d\u59cb\u5316\u65f6\u95f4\u53ef\u8fbe 100%\uff08\u5b8c\u5168\u907f\u514d\uff09<\/li><\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">\u4f7f\u7528\u6ce8\u610f\u4e8b\u9879<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">\u6839\u636e\u793e\u533a\u7684\u53cd\u9988\uff0c\u6574\u4f53\u6765\u8bf4\uff0c\u4f7f\u7528\u8fd9\u4e2a\u7279\u6027\u6211\u603b\u7ed3\u4e86 4 \u6761\u6ce8\u610f\u4e8b\u9879\uff0c\u4f9b\u5927\u5bb6\u53c2\u8003\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\u9884\u89c8\u7279\u6027\u542f\u7528<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u76ee\u524d\u8fd8\u662f\u4e00\u4e2a\u9884\u89c8\u7279\u6027\uff0c\u4e0d\u8fc7\u540e\u7eed\u5e94\u8be5\u662f\u6ca1\u5565\u6539\u52a8\u4e86\uff0c\u9884\u8ba1 JDK 26 \u6216 27 \u53ef\u80fd\u4f1a\u88ab\u5f7b\u5e95\u653e\u5f00\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code># \u7f16\u8bd1\njavac --release 26 --enable-preview Main.java\n\n# \u8fd0\u884c\njava --enable-preview Main<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\">final\u5b57\u6bb5\u7684\u91cd\u8981\u6027<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u76f4\u63a5\u770b\u4e0b\u9762\u7684\u7528\u6cd5\u5427\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>\/\/ \u6b63\u786e\uff1a\u80fd\u89e6\u53d1\u5e38\u91cf\u6298\u53e0\nstatic final LazyConstant&lt;Config&gt; CONFIG = LazyConstant.of(...);\n\n\/\/ \u9519\u8bef\uff1a\u5931\u53bb\u4f18\u5316\u6548\u679c\nstatic LazyConstant&lt;Config&gt; config = LazyConstant.of(...);<\/code><\/pre>\n\n\n\n<h2 class=\"wp-block-heading\">\u907f\u514d\u5728\u8ba1\u7b97\u51fd\u6570\u4e2d\u629b\u51fa\u5f02\u5e38<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">\u8fd9\u4e2a\u548c\u5199\u5355\u4f8b\u4e00\u6837\uff0c\u4e0d\u5efa\u8bae\u5728\u521b\u5efa\u5355\u4f8b\u65f6\u76f4\u63a5\u629b\u51fa\u5f02\u5e38\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>\/\/ \u4e0d\u63a8\u8350\nLazyConstant.of(() -&gt; {\n    if (somethingWrong) throw new RuntimeException();\n    return value;\n});\n\n\/\/ \u63a8\u8350\nLazyConstant.of(() -&gt; {\n    try {\n        return computeValue();\n    } catch (Exception e) {\n        \/\/ \u63d0\u4f9b\u9ed8\u8ba4\u503c\n        return DEFAULT_VALUE; \n    }\n});<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\">\u9650\u5236\u53cd\u5c04\u4fee\u6539<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u76ee\u524d\u5b9e\u4f8b final \u5b57\u6bb5\u4ecd\u53ef\u901a\u8fc7\u53cd\u5c04\u4fee\u6539\uff0c\u8fd9\u4f1a\u7834\u574f\u5e38\u91cf\u6298\u53e0\u3002\u4f46<code>static final<\/code>\u5b57\u6bb5\u662f\u5b89\u5168\u7684\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">\u603b\u7ed3<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">JEP 526 \u6807\u5fd7\u7740 Java \u5ef6\u8fdf\u521d\u59cb\u5316 API \u7684\u6210\u719f\u3002\u672a\u6765\u6211\u4eec\u53ef\u80fd\u770b\u5230\uff1a<\/p>\n\n\n\n<ol class=\"wp-block-list\"><li>\u8bed\u8a00\u7ea7\u652f\u6301\uff1a\u5982<code>lazy final<\/code>\u5b57\u6bb5\u58f0\u660e<\/li><li>\u5b8c\u6574\u6027\u63d0\u5347\uff1a\u9650\u5236\u53cd\u5c04\u5bf9 final \u5b57\u6bb5\u7684\u4fee\u6539\uff08JEP 500\uff09<\/li><li>\u66f4\u5e7f\u6cdb\u7684 JVM \u4f18\u5316\uff1a\u57fa\u4e8e Project Valhalla \u7684\u503c\u7c7b\u578b\u96c6\u6210<\/li><\/ol>\n\n\n\n<p class=\"wp-block-paragraph\"><code>Lazy Constants<\/code>\u4e0d\u662f\u7b80\u5355\u7684 API \u91cd\u547d\u540d\uff0c\u800c\u662f\u4e00\u6b21\u91cd\u8981\u7684\u8bbe\u8ba1\u91cd\u5851\u3002<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>\u66f4\u6e05\u6670\u7684\u8bed\u4e49\uff1a\u4ece\u5e95\u5c42\u673a\u5236\u63cf\u8ff0\u8f6c\u5411\u4f7f\u7528\u573a\u666f\u63cf\u8ff0<\/li><li>\u66f4\u5b89\u5168\u7684 API\uff1a\u79fb\u9664\u6613\u9519\u64cd\u4f5c\uff0c\u5f3a\u5236\u6784\u9020\u65f6\u63d0\u4f9b\u8ba1\u7b97\u903b\u8f91<\/li><li>\u66f4\u53cb\u597d\u7684\u5f00\u53d1\u4f53\u9a8c\uff1a\u4e0e\u96c6\u5408 API \u6df1\u5ea6\u96c6\u6210<\/li><\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">\u5bf9\u4e8e Java \u5f00\u53d1\u8005\u800c\u8a00\uff0c\u8fd9\u610f\u5473\u7740\u3002<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>\u5355\u4f8b\u6a21\u5f0f\u5b9e\u73b0\u66f4\u7b80\u5355\uff1a\u4e00\u884c\u4ee3\u7801\u89e3\u51b3\u7ebf\u7a0b\u5b89\u5168\u548c\u6027\u80fd\u95ee\u9898<\/li><li>\u5e94\u7528\u542f\u52a8\u66f4\u5feb\uff1a\u6309\u9700\u521d\u59cb\u5316\uff0c\u907f\u514d\u4e0d\u5fc5\u8981\u7684\u5f00\u9500<\/li><li>\u4ee3\u7801\u66f4\u6613\u7ef4\u62a4\uff1a\u610f\u56fe\u660e\u786e\uff0c\u51cf\u5c11 boilerplate<\/li><\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">\u672a\u6765\u5728\u9879\u76ee\u4e2d\u91c7\u7528 LazyConstants \u66ff\u4ee3\u4f20\u7edf\u7684\u53cc\u91cd\u68c0\u67e5\u9501\u5b9a\u548c\u9759\u6001\u5185\u90e8\u7c7b\u5b9e\u73b0\uff0c\u751a\u81f3\u662f Spring bean \u7684\u6574\u4f53\u5ef6\u8fdf\u521d\u59cb\u5316\u5b9e\u73b0\uff0c\u4eab\u53d7\u73b0\u4ee3 Java \u5e26\u6765\u7684\u6027\u80fd\u4e0e\u7b80\u6d01\u3002<\/p>\n<!-- <audio autoplay=\"autoplay\" height=\"100\" width=\"100\" hidden=\"true\"><source src=\"https:\/\/c.coka.la\/orAvPR.mp3\" type=\"audio\/mp3\"\/><\/audio><img decoding=\"async\" src=\"https:\/\/images.weserv.nl\/?url=https:\/\/ws3.sinaimg.cn\/large\/8fa5dcfcgy1g4em3rzar5j20ib089ae0.jpg\" alt=\"\u4e1a\u4f59\u8349\u516c\u4f17\u53f7\"\/> --><p><!-- <img decoding=\"async\" src=\"https:\/\/raw.githubusercontent.com\/xmt1139057136\/xttblog\/master\/8fa5dcfcgy1g4em3rzar5j20ib089ae0.jpg\" alt=\"\u4e1a\u4f59\u8349\u516c\u4f17\u53f7\"\/>--><img decoding=\"async\" src=\"https:\/\/saas.51autoparts.cn\/api\/admin\/sys-file\/oss\/file?fileName=84db51f8561e448f9a4fda2eff0811f9.jpg\" alt=\"\u4e1a\u4f59\u8349\u516c\u4f17\u53f7\"\/><\/p><p>\u6700\u540e\uff0c\u6b22\u8fce\u5173\u6ce8\u6211\u7684\u4e2a\u4eba\u5fae\u4fe1\u516c\u4f17\u53f7\uff1a\u4e1a\u4f59\u8349\uff08yyucao\uff09\uff01<b>\u53ef\u52a0\u4f5c\u8005\u5fae\u4fe1\u53f7\uff1a<font color=\"red\">xttblog2<\/font>\u3002\u5907\u6ce8\uff1a\u201c1\u201d\uff0c\u6dfb\u52a0\u535a\u4e3b\u5fae\u4fe1\u62c9\u4f60\u8fdb\u5fae\u4fe1\u7fa4\u3002\u5907\u6ce8\u9519\u8bef\u4e0d\u4f1a\u540c\u610f\u597d\u53cb\u7533\u8bf7\u3002<\/b>\u518d\u6b21\u611f\u8c22\u60a8\u7684\u5173\u6ce8\uff01\u540e\u7eed\u6709\u7cbe\u5f69\u5185\u5bb9\u4f1a\u7b2c\u4e00\u65f6\u95f4\u53d1\u7ed9\u60a8\uff01\u539f\u521b\u6587\u7ae0\u6295\u7a3f\u8bf7\u53d1\u9001\u81f3532009913@qq.com\u90ae\u7bb1\u3002\u5546\u52a1\u5408\u4f5c\u4e5f\u53ef\u6dfb\u52a0\u4f5c\u8005\u5fae\u4fe1\u8fdb\u884c\u8054\u7cfb\uff01<\/p><p>\u672c\u6587\u539f\u6587\u51fa\u5904\uff1a<a href=\"https:\/\/www.xttblog.com\">\u4e1a\u4f59\u8349<\/a>\uff1a &raquo; <a href=\"https:\/\/www.xttblog.com\/?p=5455\">Java \u5355\u4f8b\u6a21\u5f0f\u7ec8\u4e8e\u6709\u6551\uff01JDK 26 LazyConstants \u7ec8\u7ed3\u624b\u5199\u7ebf\u7a0b\u5b89\u5168\u65f6\u4ee3<\/a><\/p><!-- <div class=\"bd-reward-stl\"><button id=\"bdRewardBtn\"><span><\/span><\/button><\/div> -->","protected":false},"excerpt":{"rendered":"<p>Java \u53c8\u6539\u4e86\uff0c\u8fd9\u6b21\u662f JEP 502 \u7a33\u5b9a\u503c Stable Values \u6539\u4e3a JEP 526 \u60f0\u6027\u5e38\u91cf  [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5],"tags":[1334,2094,551,587,592],"class_list":["post-5455","post","type-post","status-publish","format-standard","hentry","category-java","tag-jdk8","tag-openjdk","tag-spring","tag-spring-boot","tag-springjunit4classrunner"],"_links":{"self":[{"href":"https:\/\/www.xttblog.com\/index.php?rest_route=\/wp\/v2\/posts\/5455","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.xttblog.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.xttblog.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.xttblog.com\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.xttblog.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=5455"}],"version-history":[{"count":1,"href":"https:\/\/www.xttblog.com\/index.php?rest_route=\/wp\/v2\/posts\/5455\/revisions"}],"predecessor-version":[{"id":5456,"href":"https:\/\/www.xttblog.com\/index.php?rest_route=\/wp\/v2\/posts\/5455\/revisions\/5456"}],"wp:attachment":[{"href":"https:\/\/www.xttblog.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=5455"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.xttblog.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=5455"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.xttblog.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=5455"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}